Late-season fertilization of <i>Picea mariana</i> seedlings under greenhouse culture: biomass and nutrient dynamics
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Bibliographic record
Abstract
Conventional nursery culture of containerized black spruce (Picea mariana Mill.B.S.P.) seedlings usually involves a lateseason interval, commonly called the "hardening period", when fertilization and water are withheld to promote frost-hardiness.Considerable growth may occur during this time which may lead to internal nutrient dilution, a condition often detrimental to subsequent field performance.Continued late season fertilization (at 6 or 12 mg N seedling -1 ) of seedlings during the hardening period was tested as a technique to prevent late season nutrient dilution and possibly to increase nutrient reserves.Root growth was increased much more than shoot growth during this period.Late-season fertilization raised N, P and K uptake as much as 164, 70 and 32% respectively, compared to conventionally fertilized seedlings with no late-season fertilization.Depending on dose rate and pre-hardening nutrient loading, this technique demonstrates the potential to build internal nutrient reserves in seedlings.Nutrient dilution was temporarily averted by lateseason fertilization suggesting that intensive and prolonged nutrient supplementation during the hardening period may further delay or eliminate nutrient dilution in seedlings.black spruce / hardening period / nitrogen / nutrient dilution / nutrient loading Résumé -Fertilisation en fin de saison des plants de Picea mariana cultivés en serre : dynamique de la biomasse et des éléments nutritifs.Dans les pépinières, l'élevage en container de plants de Picea mariana (Mill.B.S.P.) comporte normalement en fin de saison une phase appelée « période d'endurcissement » pendant laquelle fertilisation et arrosage sont supprimés pour améliorer la résistance au froid.La croissance, au cours de cette période, peut être importante d'où une dilution interne des éléments nutritifs affectant souvent les performances ultérieures sur le terrain.On a testé une technique consistant à prolonger la fertilisation pendant la période d'endurcissement (6 à 12 mg N par plant) pour éviter, en fin d'élevage, une dilution des éléments nutritifs, voire en augmenter la teneur.Pendant cette période, le gain de croissance du système racinaire a été plus élevé que celui des parties aériennes.Cette fertilisation en fin de saison se traduit par un prélèvement en N, P et K accru de respectivement 164, 70 et 32 % par rapport à celui observé avec le régime de fertilisation classique.Dépendant du régime de fertilité antérieur avant endurcissement et de la dose d'éléments nutritifs adoptée, cette technique démontre qu'il est possible d'agir sur la quantité de réserves en éléments des plants.Une fertilisation en fin de saison interrompt temporairement le processus de dilution des éléments.Ceci permet de penser que l'apport intensif et prolongé d'éléments pendant la période d'endurcissement peut retarder ou éviter la dilution en éléments des plants.Picea mariana / période d'endurcissement / azote / dilution des éléments nutritifs / changements nutritifs
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it